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mariadb/sql/sql_handler.cc

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/* Copyright (C) 2000-2004 MySQL AB
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/* HANDLER ... commands - direct access to ISAM */
/* TODO:
HANDLER blabla OPEN [ AS foobar ] [ (column-list) ]
the most natural (easiest, fastest) way to do it is to
compute List<Item> field_list not in mysql_ha_read
but in mysql_ha_open, and then store it in TABLE structure.
The problem here is that mysql_parse calls free_item to free all the
items allocated at the end of every query. The workaround would to
keep two item lists per THD - normal free_list and handler_items.
The second is to be freeed only on thread end. mysql_ha_open should
then do { handler_items=concat(handler_items, free_list); free_list=0; }
But !!! do_command calls free_root at the end of every query and frees up
all the sql_alloc'ed memory. It's harder to work around...
*/
/*
There are two containers holding information about open handler tables.
The first is 'thd->handler_tables'. It is a linked list of TABLE objects.
It is used like 'thd->open_tables' in the table cache. The trick is to
exchange these two lists during open and lock of tables. Thus the normal
table cache code can be used.
The second container is a HASH. It holds objects of the type TABLE_LIST.
Despite its name, no lists of tables but only single structs are hashed
(the 'next' pointer is always NULL). The reason for theis second container
is, that we want handler tables to survive FLUSH TABLE commands. A table
affected by FLUSH TABLE must be closed so that other threads are not
blocked by handler tables still in use. Since we use the normal table cache
functions with 'thd->handler_tables', the closed tables are removed from
this list. Hence we need the original open information for the handler
table in the case that it is used again. This information is handed over
to mysql_ha_open() as a TABLE_LIST. So we store this information in the
second container, where it is not affected by FLUSH TABLE. The second
container is implemented as a hash for performance reasons. Consequently,
we use it not only for re-opening a handler table, but also for the
HANDLER ... READ commands. For this purpose, we store a pointer to the
TABLE structure (in the first container) in the TBALE_LIST object in the
second container. When the table is flushed, the pointer is cleared.
*/
#include "mysql_priv.h"
#include "sql_select.h"
#include <assert.h>
#define HANDLER_TABLES_HASH_SIZE 120
static enum enum_ha_read_modes rkey_to_rnext[]=
{ RNEXT_SAME, RNEXT, RPREV, RNEXT, RPREV, RNEXT, RPREV, RPREV };
#define HANDLER_TABLES_HACK(thd) { \
TABLE *tmp=thd->open_tables; \
thd->open_tables=thd->handler_tables; \
thd->handler_tables=tmp; }
static int mysql_ha_flush_table(THD *thd, TABLE **table_ptr, uint mode_flags);
/*
Get hash key and hash key length.
SYNOPSIS
mysql_ha_hash_get_key()
tables Pointer to the hash object.
key_len_p (out) Pointer to the result for key length.
first Unused.
DESCRIPTION
The hash object is an TABLE_LIST struct.
The hash key is the alias name.
The hash key length is the alias name length plus one for the
terminateing NUL character.
RETURN
Pointer to the TABLE_LIST struct.
*/
static char *mysql_ha_hash_get_key(TABLE_LIST *tables, uint *key_len_p,
my_bool first __attribute__((unused)))
{
*key_len_p= strlen(tables->alias) + 1 ; /* include '\0' in comparisons */
return tables->alias;
}
/*
Free an hash object.
SYNOPSIS
mysql_ha_hash_free()
tables Pointer to the hash object.
DESCRIPTION
The hash object is an TABLE_LIST struct.
RETURN
Nothing
*/
static void mysql_ha_hash_free(TABLE_LIST *tables)
{
my_free((char*) tables, MYF(0));
}
/*
Open a HANDLER table.
SYNOPSIS
mysql_ha_open()
thd Thread identifier.
tables A list of tables with the first entry to open.
reopen Re-open a previously opened handler table.
DESCRIPTION
Though this function takes a list of tables, only the first list entry
will be opened.
'reopen' is set when a handler table is to be re-opened. In this case,
'tables' is the pointer to the hashed TABLE_LIST object which has been
saved on the original open.
'reopen' is also used to suppress the sending of an 'ok' message or
error messages.
RETURN
0 ok
!= 0 error
*/
int mysql_ha_open(THD *thd, TABLE_LIST *tables, bool reopen)
{
TABLE_LIST *hash_tables;
char *db, *name, *alias;
uint dblen, namelen, aliaslen, counter;
int err;
DBUG_ENTER("mysql_ha_open");
DBUG_PRINT("enter",("'%s'.'%s' as '%s' reopen: %d",
tables->db, tables->real_name, tables->alias,
(int) reopen));
if (! hash_inited(&thd->handler_tables_hash))
{
/*
HASH entries are of type TABLE_LIST.
*/
if (hash_init(&thd->handler_tables_hash, &my_charset_latin1,
HANDLER_TABLES_HASH_SIZE, 0, 0,
(hash_get_key) mysql_ha_hash_get_key,
(hash_free_key) mysql_ha_hash_free, 0))
goto err;
}
else if (! reopen) /* Otherwise we have 'tables' already. */
{
if (hash_search(&thd->handler_tables_hash, (byte*) tables->alias,
strlen(tables->alias) + 1))
{
DBUG_PRINT("info",("duplicate '%s'", tables->alias));
if (! reopen)
my_printf_error(ER_NONUNIQ_TABLE, ER(ER_NONUNIQ_TABLE),
MYF(0), tables->alias);
goto err;
}
}
/*
open_tables() will set 'tables->table' if successful.
It must be NULL for a real open when calling open_tables().
*/
DBUG_ASSERT(! tables->table);
HANDLER_TABLES_HACK(thd);
err=open_tables(thd, tables, &counter);
HANDLER_TABLES_HACK(thd);
if (err)
goto err;
/* There can be only one table in '*tables'. */
if (! (tables->table->file->table_flags() & HA_CAN_SQL_HANDLER))
{
if (! reopen)
my_printf_error(ER_ILLEGAL_HA,ER(ER_ILLEGAL_HA),MYF(0), tables->alias);
mysql_ha_close(thd, tables);
goto err;
}
if (! reopen)
{
/* copy the TABLE_LIST struct */
dblen= strlen(tables->db) + 1;
namelen= strlen(tables->real_name) + 1;
aliaslen= strlen(tables->alias) + 1;
if (!(my_multi_malloc(MYF(MY_WME),
&hash_tables, sizeof(*hash_tables),
&db, dblen,
&name, namelen,
&alias, aliaslen,
NullS)))
goto err;
/* structure copy */
*hash_tables= *tables;
hash_tables->db= db;
hash_tables->real_name= name;
hash_tables->alias= alias;
memcpy(hash_tables->db, tables->db, dblen);
memcpy(hash_tables->real_name, tables->real_name, namelen);
memcpy(hash_tables->alias, tables->alias, aliaslen);
/* add to hash */
if (my_hash_insert(&thd->handler_tables_hash, (byte*) hash_tables))
{
mysql_ha_close(thd, tables);
goto err;
}
}
if (! reopen)
send_ok(thd);
DBUG_PRINT("exit",("OK"));
DBUG_RETURN(0);
err:
DBUG_PRINT("exit",("ERROR"));
DBUG_RETURN(-1);
}
/*
Close a HANDLER table.
SYNOPSIS
mysql_ha_close()
thd Thread identifier.
tables A list of tables with the first entry to close.
DESCRIPTION
Though this function takes a list of tables, only the first list entry
will be closed. Broadcasts a COND_refresh condition.
RETURN
0 ok
!= 0 error
*/
int mysql_ha_close(THD *thd, TABLE_LIST *tables)
{
TABLE_LIST *hash_tables;
TABLE **table_ptr;
DBUG_ENTER("mysql_ha_close");
DBUG_PRINT("enter",("'%s'.'%s' as '%s'",
tables->db, tables->real_name, tables->alias));
if ((hash_tables= (TABLE_LIST*) hash_search(&thd->handler_tables_hash,
(byte*) tables->alias,
strlen(tables->alias) + 1)))
{
/*
Though we could take the table pointer from hash_tables->table,
we must follow the thd->handler_tables chain anyway, as we need the
address of the 'next' pointer referencing this table
for close_thread_table().
*/
for (table_ptr= &(thd->handler_tables);
*table_ptr && (*table_ptr != hash_tables->table);
table_ptr= &(*table_ptr)->next);
#if MYSQL_VERSION_ID < 40100
if (*tables->db && strcmp(hash_tables->db, tables->db))
{
DBUG_PRINT("info",("wrong db"));
hash_tables= NULL;
}
else
#endif
{
if (*table_ptr)
{
(*table_ptr)->file->ha_index_or_rnd_end();
VOID(pthread_mutex_lock(&LOCK_open));
if (close_thread_table(thd, table_ptr))
{
/* Tell threads waiting for refresh that something has happened */
VOID(pthread_cond_broadcast(&COND_refresh));
}
VOID(pthread_mutex_unlock(&LOCK_open));
}
hash_delete(&thd->handler_tables_hash, (byte*) hash_tables);
}
}
if (! hash_tables)
{
#if MYSQL_VERSION_ID < 40100
char buff[MAX_DBKEY_LENGTH];
if (*tables->db)
strxnmov(buff, sizeof(buff), tables->db, ".", tables->real_name, NullS);
else
strncpy(buff, tables->alias, sizeof(buff));
my_printf_error(ER_UNKNOWN_TABLE, ER(ER_UNKNOWN_TABLE), MYF(0),
buff, "HANDLER");
#else
my_printf_error(ER_UNKNOWN_TABLE, ER(ER_UNKNOWN_TABLE), MYF(0),
tables->alias, "HANDLER");
#endif
DBUG_PRINT("exit",("ERROR"));
DBUG_RETURN(-1);
}
send_ok(thd);
DBUG_PRINT("exit", ("OK"));
DBUG_RETURN(0);
}
/*
Read from a HANDLER table.
SYNOPSIS
mysql_ha_read()
thd Thread identifier.
tables A list of tables with the first entry to read.
mode
keyname
key_expr
ha_rkey_mode
cond
select_limit
offset_limit
RETURN
0 ok
!= 0 error
*/
int mysql_ha_read(THD *thd, TABLE_LIST *tables,
enum enum_ha_read_modes mode, char *keyname, List<Item> *key_expr,
enum ha_rkey_function ha_rkey_mode, Item *cond,
ha_rows select_limit,ha_rows offset_limit)
{
TABLE_LIST *hash_tables;
TABLE **table_ptr;
TABLE *table;
MYSQL_LOCK *lock;
List<Item> list;
Protocol *protocol= thd->protocol;
char buff[MAX_FIELD_WIDTH];
String buffer(buff, sizeof(buff), system_charset_info);
int err, keyno= -1;
uint num_rows;
byte *key;
uint key_len;
DBUG_ENTER("mysql_ha_read");
DBUG_PRINT("enter",("'%s'.'%s' as '%s'",
tables->db, tables->real_name, tables->alias));
LINT_INIT(key);
LINT_INIT(key_len);
list.push_front(new Item_field(NULL,NULL,"*"));
List_iterator<Item> it(list);
it++;
if ((hash_tables= (TABLE_LIST*) hash_search(&thd->handler_tables_hash,
(byte*) tables->alias,
strlen(tables->alias) + 1)))
{
table= hash_tables->table;
DBUG_PRINT("info-in-hash",("'%s'.'%s' as '%s' tab %p",
hash_tables->db, hash_tables->real_name,
hash_tables->alias, table));
if (!table)
{
/*
The handler table has been closed. Re-open it.
*/
if (mysql_ha_open(thd, hash_tables, 1))
{
DBUG_PRINT("exit",("reopen failed"));
goto err0;
}
table= hash_tables->table;
DBUG_PRINT("info",("re-opened '%s'.'%s' as '%s' tab %p",
hash_tables->db, hash_tables->real_name,
hash_tables->alias, table));
}
#if MYSQL_VERSION_ID < 40100
if (*tables->db && strcmp(table->table_cache_key, tables->db))
{
DBUG_PRINT("info",("wrong db"));
table= NULL;
}
#endif
}
else
table= NULL;
if (!table)
{
#if MYSQL_VERSION_ID < 40100
char buff[MAX_DBKEY_LENGTH];
if (*tables->db)
strxnmov(buff, sizeof(buff), tables->db, ".", tables->real_name, NullS);
else
strncpy(buff, tables->alias, sizeof(buff));
my_printf_error(ER_UNKNOWN_TABLE, ER(ER_UNKNOWN_TABLE), MYF(0),
buff, "HANDLER");
#else
my_printf_error(ER_UNKNOWN_TABLE, ER(ER_UNKNOWN_TABLE), MYF(0),
tables->alias, "HANDLER");
#endif
goto err0;
}
tables->table=table;
HANDLER_TABLES_HACK(thd);
lock= mysql_lock_tables(thd, &tables->table, 1, 0);
HANDLER_TABLES_HACK(thd);
if (!lock)
goto err0; // mysql_lock_tables() printed error message already
if (cond && ((!cond->fixed &&
cond->fix_fields(thd, tables, &cond)) || cond->check_cols(1)))
goto err0;
if (keyname)
{
if ((keyno=find_type(keyname, &table->keynames, 1+2)-1)<0)
{
my_printf_error(ER_KEY_DOES_NOT_EXITS,ER(ER_KEY_DOES_NOT_EXITS),MYF(0),
keyname,tables->alias);
goto err0;
}
}
if (insert_fields(thd,tables,tables->db,tables->alias,&it))
goto err0;
select_limit+=offset_limit;
protocol->send_fields(&list,1);
/*
In ::external_lock InnoDB resets the fields which tell it that
the handle is used in the HANDLER interface. Tell it again that
we are using it for HANDLER.
*/
table->file->init_table_handle_for_HANDLER();
for (num_rows=0; num_rows < select_limit; )
{
switch (mode) {
case RNEXT:
if (table->file->inited != handler::NONE)
{
err=keyname ?
table->file->index_next(table->record[0]) :
table->file->rnd_next(table->record[0]);
break;
}
/* else fall through */
case RFIRST:
if (keyname)
{
table->file->ha_index_or_rnd_end();
table->file->ha_index_init(keyno);
err=table->file->index_first(table->record[0]);
}
else
{
table->file->ha_index_or_rnd_end();
if (!(err=table->file->ha_rnd_init(1)))
err=table->file->rnd_next(table->record[0]);
}
mode=RNEXT;
break;
case RPREV:
DBUG_ASSERT(keyname != 0);
if (table->file->inited != handler::NONE)
{
err=table->file->index_prev(table->record[0]);
break;
}
/* else fall through */
case RLAST:
DBUG_ASSERT(keyname != 0);
table->file->ha_index_or_rnd_end();
table->file->ha_index_init(keyno);
err=table->file->index_last(table->record[0]);
mode=RPREV;
break;
case RNEXT_SAME:
/* Continue scan on "(keypart1,keypart2,...)=(c1, c2, ...) */
DBUG_ASSERT(keyname != 0);
err= table->file->index_next_same(table->record[0], key, key_len);
break;
case RKEY:
{
DBUG_ASSERT(keyname != 0);
KEY *keyinfo=table->key_info+keyno;
KEY_PART_INFO *key_part=keyinfo->key_part;
if (key_expr->elements > keyinfo->key_parts)
{
my_printf_error(ER_TOO_MANY_KEY_PARTS,ER(ER_TOO_MANY_KEY_PARTS),
MYF(0),keyinfo->key_parts);
goto err;
}
List_iterator<Item> it_ke(*key_expr);
Item *item;
for (key_len=0 ; (item=it_ke++) ; key_part++)
{
// 'item' can be changed by fix_fields() call
if ((!item->fixed &&
item->fix_fields(thd, tables, it_ke.ref())) ||
(item= *it_ke.ref())->check_cols(1))
goto err;
if (item->used_tables() & ~RAND_TABLE_BIT)
{
my_error(ER_WRONG_ARGUMENTS,MYF(0),"HANDLER ... READ");
goto err;
}
(void) item->save_in_field(key_part->field, 1);
key_len+=key_part->store_length;
}
if (!(key= (byte*) thd->calloc(ALIGN_SIZE(key_len))))
{
send_error(thd,ER_OUTOFMEMORY);
goto err;
}
key_copy(key, table, keyno, key_len);
table->file->ha_index_or_rnd_end();
table->file->ha_index_init(keyno);
err=table->file->index_read(table->record[0],
key,key_len,ha_rkey_mode);
mode=rkey_to_rnext[(int)ha_rkey_mode];
break;
}
default:
send_error(thd,ER_ILLEGAL_HA);
goto err;
}
if (err == HA_ERR_RECORD_DELETED)
continue;
if (err)
{
if (err != HA_ERR_KEY_NOT_FOUND && err != HA_ERR_END_OF_FILE)
{
sql_print_error("mysql_ha_read: Got error %d when reading table '%s'",
err, tables->real_name);
table->file->print_error(err,MYF(0));
goto err;
}
goto ok;
}
if (cond && !cond->val_int())
continue;
if (num_rows >= offset_limit)
{
Item *item;
protocol->prepare_for_resend();
it.rewind();
while ((item=it++))
{
if (item->send(thd->protocol, &buffer))
{
protocol->free(); // Free used
my_error(ER_OUT_OF_RESOURCES,MYF(0));
goto err;
}
}
protocol->write();
}
num_rows++;
}
ok:
mysql_unlock_tables(thd,lock);
send_eof(thd);
DBUG_PRINT("exit",("OK"));
DBUG_RETURN(0);
err:
mysql_unlock_tables(thd,lock);
err0:
DBUG_PRINT("exit",("ERROR"));
DBUG_RETURN(-1);
}
/*
Flush (close) a list of HANDLER tables.
SYNOPSIS
mysql_ha_flush()
thd Thread identifier.
tables The list of tables to close. If NULL,
close all HANDLER tables [marked as flushed].
mode_flags MYSQL_HA_CLOSE_FINAL finally close the table.
MYSQL_HA_REOPEN_ON_USAGE mark for reopen.
MYSQL_HA_FLUSH_ALL flush all tables, not only
those marked for flush.
is_locked If LOCK_open is locked.
DESCRIPTION
The list of HANDLER tables may be NULL, in which case all HANDLER
tables are closed (if MYSQL_HA_FLUSH_ALL) is set.
If 'tables' is NULL and MYSQL_HA_FLUSH_ALL is not set,
all HANDLER tables marked for flush are closed.
Broadcasts a COND_refresh condition, for every table closed.
NOTE
Since mysql_ha_flush() is called when the base table has to be closed,
we compare real table names, not aliases. Hence, database names matter.
RETURN
0 ok
*/
int mysql_ha_flush(THD *thd, TABLE_LIST *tables, uint mode_flags,
bool is_locked)
{
TABLE_LIST *tmp_tables;
TABLE **table_ptr;
bool did_lock= FALSE;
DBUG_ENTER("mysql_ha_flush");
DBUG_PRINT("enter", ("tables: %p mode_flags: 0x%02x", tables, mode_flags));
if (tables)
{
/* Close all tables in the list. */
for (tmp_tables= tables ; tmp_tables; tmp_tables= tmp_tables->next)
{
DBUG_PRINT("info-in-tables-list",("'%s'.'%s' as '%s'",
tmp_tables->db, tmp_tables->real_name,
tmp_tables->alias));
/* Close all currently open handler tables with the same base table. */
table_ptr= &(thd->handler_tables);
while (*table_ptr)
{
if ((! *tmp_tables->db ||
! my_strcasecmp(&my_charset_latin1, (*table_ptr)->table_cache_key,
tmp_tables->db)) &&
! my_strcasecmp(&my_charset_latin1, (*table_ptr)->real_name,
tmp_tables->real_name))
{
DBUG_PRINT("info",("*table_ptr '%s'.'%s' as '%s'",
(*table_ptr)->table_cache_key,
(*table_ptr)->real_name,
(*table_ptr)->table_name));
/* The first time it is required, lock for close_thread_table(). */
if (! did_lock && ! is_locked)
{
VOID(pthread_mutex_lock(&LOCK_open));
did_lock= TRUE;
}
mysql_ha_flush_table(thd, table_ptr, mode_flags);
continue;
}
table_ptr= &(*table_ptr)->next;
}
/* end of handler_tables list */
}
/* end of flush tables list */
}
else
{
/* Close all currently open tables [which are marked for flush]. */
table_ptr= &(thd->handler_tables);
while (*table_ptr)
{
if ((mode_flags & MYSQL_HA_FLUSH_ALL) ||
((*table_ptr)->version != refresh_version))
{
/* The first time it is required, lock for close_thread_table(). */
if (! did_lock && ! is_locked)
{
VOID(pthread_mutex_lock(&LOCK_open));
did_lock= TRUE;
}
mysql_ha_flush_table(thd, table_ptr, mode_flags);
continue;
}
table_ptr= &(*table_ptr)->next;
}
}
/* Release the lock if it was taken by this function. */
if (did_lock)
VOID(pthread_mutex_unlock(&LOCK_open));
DBUG_RETURN(0);
}
/*
Flush (close) a table.
SYNOPSIS
mysql_ha_flush_table()
thd Thread identifier.
table The table to close.
mode_flags MYSQL_HA_CLOSE_FINAL finally close the table.
MYSQL_HA_REOPEN_ON_USAGE mark for reopen.
DESCRIPTION
Broadcasts a COND_refresh condition, for every table closed.
The caller must lock LOCK_open.
RETURN
0 ok
*/
static int mysql_ha_flush_table(THD *thd, TABLE **table_ptr, uint mode_flags)
{
TABLE_LIST *hash_tables;
TABLE *table= *table_ptr;
DBUG_ENTER("mysql_ha_flush_table");
DBUG_PRINT("enter",("'%s'.'%s' as '%s' flags: 0x%02x",
table->table_cache_key, table->real_name,
table->table_name, mode_flags));
if ((hash_tables= (TABLE_LIST*) hash_search(&thd->handler_tables_hash,
(byte*) table->table_name,
strlen(table->table_name) + 1)))
{
if (! (mode_flags & MYSQL_HA_REOPEN_ON_USAGE))
{
/* This is a final close. Remove from hash. */
hash_delete(&thd->handler_tables_hash, (byte*) hash_tables);
}
else
{
/* Mark table as closed, ready for re-open. */
hash_tables->table= NULL;
}
}
safe_mutex_assert_owner(&LOCK_open);
(*table_ptr)->file->ha_index_or_rnd_end();
if (close_thread_table(thd, table_ptr))
{
/* Tell threads waiting for refresh that something has happened */
VOID(pthread_cond_broadcast(&COND_refresh));
}
DBUG_RETURN(0);
}
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